package budget

import (
	"context"
	"spend-sparrow/internal/auth_types"
	"spend-sparrow/internal/core"

	"github.com/google/uuid"
)

type Service interface {
	Add(ctx context.Context, user *auth_types.User, budget Budget) (*Budget, error)
	Update(ctx context.Context, user *auth_types.User, budget Budget) (*Budget, error)
	Delete(ctx context.Context, user *auth_types.User, budgetId uuid.UUID) error
	Get(ctx context.Context, user *auth_types.User, budgetId uuid.UUID) (*Budget, error)
	GetAll(ctx context.Context, user *auth_types.User) ([]Budget, error)
}

type ServiceImpl struct {
	db     Db
	clock  core.Clock
	random core.Random
}

func NewService(db Db, random core.Random, clock core.Clock) Service {
	return ServiceImpl{
		db:     db,
		clock:  clock,
		random: random,
	}
}

func (s ServiceImpl) Add(ctx context.Context, user *auth_types.User, budget Budget) (*Budget, error) {
	if user == nil {
		return nil, core.ErrUnauthorized
	}

	isValid := s.isBudgetValid(budget)
	if !isValid {
		return nil, core.ErrBadRequest
	}

	newId, err := s.random.UUID(ctx)
	if err != nil {
		return nil, core.ErrInternal
	}

	budget.Id = newId
	budget.UserId = user.Id
	budget.CreatedBy = user.Id
	budget.CreatedAt = s.clock.Now()

	return s.db.Insert(ctx, budget)
}

func (s ServiceImpl) Update(ctx context.Context, user *auth_types.User, budget Budget) (*Budget, error) {
	if user == nil {
		return nil, core.ErrUnauthorized
	}
	if user.Id != budget.UserId {
		return nil, core.ErrBadRequest
	}

	isValid := s.isBudgetValid(budget)
	if !isValid {
		return nil, core.ErrBadRequest
	}

	budget.UpdatedBy = &user.Id
	now := s.clock.Now()
	budget.UpdatedAt = &now

	return s.db.Update(ctx, budget)
}

func (s ServiceImpl) Delete(ctx context.Context, user *auth_types.User, budgetId uuid.UUID) error {
	if user == nil {
		return core.ErrUnauthorized
	}

	return s.db.Delete(ctx, user.Id, budgetId)
}

func (s ServiceImpl) Get(ctx context.Context, user *auth_types.User, budgetId uuid.UUID) (*Budget, error) {
	if user == nil {
		return nil, core.ErrUnauthorized
	}

	return s.db.Get(ctx, user.Id, budgetId)
}

func (s ServiceImpl) GetAll(ctx context.Context, user *auth_types.User) ([]Budget, error) {
	if user == nil {
		return nil, core.ErrUnauthorized
	}

	return s.db.GetAll(ctx, user.Id)
}

func (s ServiceImpl) isBudgetValid(budget Budget) bool {
	if budget.Description != "" {
		err := core.ValidateString(budget.Description, "description")
		if err != nil {
			return false
		}
	} else if budget.Value < 0 {
		return false
	}

	return true
}